Brake



April z5, 1944. D. J. AYERS 2,347,388

BRAKE v Filedy Sept. 4, 1941 I 2 Sheets-Sheet 2 INm-JNTOR BY a/vfaJAyf/Ps ATTORNEY A Patented Apr. 25, 1944 invention .reatesjto ,hrakes," and particw.

larly-to those portions ,of brakeswhere the frictional; stopping force is directly-exerted.

`.Anobject ofthe invention is to furnish an hy` draulic brake in whichstwofshoes are applied withA equalized -force exertedsimultaneously at opposite sides of -fthe'brake vvloyrai mechanism actuated bya singlezhydraulic cylinderg-ff" iA second object of my invention is to provide a-'brake having a plurality f of `shoes which are individually shiftable to anchor at dierentipoints and izo/Which applying :force istransmitted by one or more servo'applyingdevices. Thus, the hydraulic `cylinder vmentioned abovey serves `to move one or more servo elements against a rotatanaemia-Ayers," south emailed., aangiften-` to" f ill-*Bendix Aviation Cermraition, `South B vglad., a corporation ci Delaware 'Y lllicatlon ISeptember 4, ,Serial v1Y0-f@095:68

j g iclaimg." (cries-Lier# particu,

ing-brake drum, and '-therotation of the drum y tends tocarrythe servo-brake elements around the brake, the movement of the said brake elements being adapted-to exerten applying force ono'neor more brake shoes.' f

A featurefof my invention is'the connecting oi' acylindercasing to a servo device and the con necting of a piston reciprocable in the casing to a second-servo device at the opposite vside of the brake from the iirstservodevice. Other objectsand features of my invention will be apparent during the course of the following descriptiomreference being had ther'ein to the accompanying drawingain which:

'Figure' l is a section taken through abrake assembly on the plane just inside the head of a brake drum, showing brake shoes inside elevation; f

Figure 2 is a section taken on the line 2 2 of Figure 1; s l

Figure 3 is a section taken on the line -f or' Fignrel; and

Figure liis a section taken on the line l-ll of 4Figurel.

Figure l, as illustratedis awheel brake assemblycomprisinga rotatable brake drum ti, a 'non-rotatablesupportor backing plate i2, a plurality of. anchors i3. mounted in spaced positions von the backing iplate, a plurality of individually shiftable-brake shoes i4 adapted to be moved into frictional contact vwith the brake drum 4il Aand adaptedto'anchorl at one end or the other von one of the/anchors I3 according to thedirection of `rotation-of the, brake drum at the time the shoes contact the drum, and applying means for moving the shoes against the drum to inhibit Adrum rotation-.1 `It will be. noted that an anchor I3 is provided adjacent-each end of each shoe M sothat the shoesmay anchor at either end aci cording tothe direction of drum rotation. A plurality of positioning or retaining springs l5 normally holdeach end of each shoe against its adjacent anchor to maintain the shoes in brake released position. Each shoe Il comprises a web end,

la, 1 whit'zh,A transIx'ii-tSf-the". l torque tothe anchorsiarin'i lab ,and I .A gy'orv friction facing portion. iclgEah.hofmlf M has at. each of its ends a pairotjpronglik jections idd, the .purpose `'of'jwhic'ilfi Will ppe presently. l

. Each of the anchors i3 (see-Figureliignay c` .prise a body portion i3d riveted or othervlisie`v securedvto the backingplatevi-Z lanche, projecting button tab on the topof. the anchortoeatch..onine end of the associatedtension springig I,'.'Lhee other end of spring i5 may extendthrough one of a plurality of openings it. inthe v lebs off the; shoes ida, and said springendrrnay contact the, shoe web on the side of the wehawayromthe body of the spring, `to prevent unwarranted later?. al movement of 'the spring away from theshoe web. The shoewebs extend finto openings.9,"Fy in the body portions .23a of the anchorsso that lateral positioning of the shoes is in partlaccome. plished by the anchors. v 1;. The applying means or means `for moving `the shoes against the brake drum includes a hydraulic cylinder or casing it having reciprocable therein a piston i9. The casing iB vhas an cartina/"ex,- tending therefrom .which is secured rbysuitalcle means to a servo devicevor shoe '28.v The .piston IS is connected by a screw-2i or other suitable means to a yoke girwhich vhas curved side portions extending around'the center-of the ,brake assembly to the sideuof the brake opposite A,the hydraulic cylinder and piston unit. At .the side of the brake assembly opposite 'the said cylinder and piston unit, the yoke hasan ear @whichy is secured by `suitable .rneans to 'a' servofdevice or shoe 263. Each o ythe servo .shoes 2@ and 2t eX- tends betweenadjacent ends of -th'e anchoring shoes iii and each of the said-servo shoes@ and @il comprises a web portion-iii which is secured to the eer or the cylinder casing oryolierespec-y tively, as described above, arm portion 25m-and a friction lining portion 2%. The f projections id on the ends of thezrims of the shoes M embrace the webs of theservo shoes 20 and' to position the servo shoes laterally and to'aidin holding the Whole assembly in position. A pair of return springs` '35 under. tensionconnect :the servo shoe 20 to the adjacent' side ofltheyokev 22, to normally hold the pistonIQ--drawniullyinto the cylinder i8'. v.Ity -may'fbef-wellz tio-point `out that the positions of 'thecylinder/ and'lpistonfan'd their connection to the'shoe's and yoke-might be reversed without in-'any sense departing from the Vscopeof my invention.`l f. i,

With particular'reference to themanner of 'connecting the servo'l shoes tothe `piston 'and' cylinder unit', I `have llust'ratedthevear'-23^ofthe lower portion of the yoke22infFigu1-e 3 as having .a pair of arms or forks 26 which clamp the web of the servo shoes 24 between them. In Figure 2 I have illustrated the ear I8a of the casing or cylinder I8 as having a pair of arms 21 which clamp between them the web of the servo shoe 20.

A iiuld inlet 28 may be provided in 4the side v of the casing or cylinder I8 to admit fluid underv pressure which operates between the upper end of the piston I9 and the wall of the cylinder I8.

On the said upper end of the piston I8 is a seallng cup 28 of the usual type above which sealing cup is a compression spring 30 which holds the cup in place and maintains the volume of iluidfilled space between the piston and cylinder at a predetermined minimum. A bleeder inlet 3| may be provided in the cylinder I8 at the highest point. Through the inlet 28 the interior of the cylinder I8 may be connected to a hydraulic pressure system of the well known type so that fluid under pressure may be admitted to the space between the cylinder and piston to cause relative movement therebetween.

The operation of my improved brake device is as follows:

When it is desired to operate the brake, fluid under pressure may be (forced into the space be-v tween the upper end of the piston I9 andthe casing of the cylinder I8. The pressure exerted by this fluid tends to push the cylinder upward and the piston downward with the result that the servo shoes 20 and 24 are simultaneously moved against the brake drum II. If the vehicle is in motion and the brake drum is rotating, the servo '"drum is opposite the direction of the arrow, the

left shoe I4 will anchor at the top of the brake and right shoe M will anchor at the bottom of the brake. `In either case, both shoes I4 are selfenergizing, i. e., the Wrapping effect of the drum rotation tends to increase the frictional stopping force. Upon diminution of the fluid pressure in the cylinder I8, the return springs 35,move the servo shoes 20 and 24 back to released position,

and springs I position the shoes Il.

Although I have described a single. embodiment of my invention, it will be readily apparent'that numerous other applications of the fundamental idea may be made. tend to limit the scope of my invention to the embodiment discussed herein, but only by the terms of the appended claims.

Iclaim:

1. A brake assembly comprising, in combination, a rotatable brake drum, two main shoes therein each of which includes a web and a rim and each of which is shiftable to anchor at one end or the other depending on the direction of drum rotation, anchors against which the main shoes rest in release and whichtake the anchoring torque of the shoes when they are applied to the drum, two servo shoes each between the main shoes at one end thereof, the rims of said main shoes having extensions at each end thereof which hold the servo shoes in lateral alignment with the main shoes to maintain surface contact between the I therefore do not inwebs of the servo shoes-and the webs of the main shoes, and means to spread said servo shoes to contact the drum whereby the drum as it rotates rotates the servo shoes which apply the main shoes for either direction of drum rotation, said means comprising a hydraulically actuated member fixed to one of said servo shoes and a second hydraulically actuated member movable relatively to the rst and engaging a part ilxed to the other servo shoe.

2. A brake assembly comprising in combination, a rotatable brake drum, two main shoes therein each of which includes a web and a rim and each of which is shiftable to anchor at one end or the other depending on the direction of drum rotation, anchors which take the anchoring torque of the main shoes when they are applied to the drum, two servo shoes each between the main shoes at one end thereof, the rims of said main shoes having extensions at each end thereof which hold the servo shoes in lateral alignment. with the main shoes to maintain surface contact between the webs of the servo shoes and the webs of the main shoes, andmeans to spread said servo shoes to contact the drum whereby the drum as'it rotates rotates the servo shoes which apply the main shoes for eitherdirection of drum rotation, said means comprising a hydraulically actuated member flxed to one of said servo shoes and a second hydraulically actuated member movable relatively tothe first and engaging a part fixed to the other servo shoe.

3. A' brake assembly comprising in combination, a rotatable brake drum, two main shoes therein each of which includes a web and a riml and each of which is shiftable to anchor at one; end or the other depending on the direction of drum rotation, anchors which take the anchoring torque of the main shoes when they are applied to the drum, two servo shoes each between the main shoes at one end thereof, the rims of said maink shoes having extensions at each end thereof which hold the servo shoes in lateral alignment with the main shoes to maintain surface contact between the webs of the servo shoes and the webs of the main shoes, and means to spread said servo shoes to contact the drum whereby the drum as it rotates rotates the servo s'hoes which apply the main shoes for either direction of drum rotation.

4. A brake assembly comprising in combination, a rotatable brake drum, two main shoes therein each of which includes a web and a rim and each of which is shiftable to anchor at one end or the other depending on the direction of drum rotation. anchors against which the main shoes rest in release and which take the anchoring torque of the shoes when they are applied to the drum, two servo shoes each between the main shoes at one end thereof, the rims of said main shoes having extensions at each end thereof which hold the servo shoes in lateral alignment with the main shoes to maintain surface contact between the Webs of the servo shoes and the webs of the main shoes, the webs of said main shoes being notched at each end to accommodate the anchors, and means to spread said servo shoes to contact the drum whereby the drum as it rotates rotates the servo shoes which apply the main shoes for either direction of drum rotation.

DONALD Jv. AYERS. 

